The present invention relates to a zoom lens. Specifically, the present invention relates to the same suitable for being applied to video cameras, digital cameras or the like. Further, the present invention also relates to an image pickup apparatus having a zoom lens the full length of which is kept constant during activation of variable power and focusing.
In recent years, miniaturing and thickness reduction of zoom lenses employed in digital cameras and video cameras have been developed.
On the other hand, zoom lenses have been required to have widened angles of view and increased variable power ratios with needs of miniaturing and thickness reduction being satisfied.
Five group type zoom lenses employing lens arrangement in which refractive power is positive, negative, positive, negative, positive, in order from the object side toward the image side have been known conventionally as zoom lenses which keep up with needs of widening angle of view and increasing variable power ratio, as disclosed in Patent Document 1 (JP-B-3598971)-Document 5 (JP-A-2009-282398).
Focal length at the wide angle end and variable power ratio are scored as follows, being expressed in converted values which would be marked under a condition of 35 mm film size at an image plane.
JP-B-3598971 (Patent Document 1) discloses a zoom lens which gives 35 mm-film-size-converted focal length of 29.6 mm at the wide angle end and variable power ratio of 11.4 times.
JP-A-2008-304706 (Patent Document 2) discloses a zoom lens which gives 35 mm-film-size-converted focal length of 28.4 mm at the wide angle end and variable power ratio of 12 times.
JP-A-2008-304708 (Patent Document 3) discloses a zoom lens which gives 35 mm-film-size-converted focal length of 28.4 mm at the wide angle end and variable power ratio of 12 times.
JP-A-2009-115958 (Patent Document 4) discloses a zoom lens which gives 35 mm-film-size-converted focal length of 31 mm at the wide angle end and variable power ratio of 17.5 times.
JP-A-2009-282398 (Patent Document 5) discloses a zoom lens which gives 35 mm-film-size-converted focal length of 27 mm at the wide angle end and variable power ratio of 19.4 times.